Polyurethane polyester elastomer: Innovative environmental friendly wood adhesive from modified PETs and hydroxyl liquid natural rubber polyols

Polyester polyurethane elastomer adhesives were prepared from hydroxyl liquid natural rubber and modified poly(ethylene terephthalate) with polymeric MDI. The starting materials and PU adducts were characterized by FT-IR in transition and ATR modes. The effect of the amount of hydroxyl groups on modified rubber, types of modified PET, and NCO/OH ratios were studied by wood-to-wood adhesion shear strength. The chemical resistance and green strength of PU adhesives were also analyzed by lab shear test. It was found that the synthesized carboxyl terminated PET and modified rubber contained 50% hydroxyl content with polymeric MDI in optimized NCO/OH molar ratio (0.45:0.55:0.75 by mole) presented the highest wood adhesive shear strength and chemical resistance, and present 83% of its maximum strength within only 12 h.